With the development of information technology, mobile terminals have increasingly rich functions, and various applications of new technologies and new functions are presented in different manners. Force touch (3D-touch) technology can sense the intensity of pressing, and thereby can achieve various functions based on different intensities, increasing user's experience.
Currently, a force touch sensor based on piezoelectric effect is typically used to achieve multi-point touch and pressure sensing functions. The force touch sensor comprises a driving electrode, a sensing electrode, and a piezoelectric material layer disposed between the driving electrode and the sensing electrode, wherein the piezoelectric material layer is an insulator.
When a pressure is applied to the force touch sensor, positive and negative charges are respectively accumulated at two ends of the piezoelectric material layer in the pressure-applying direction, and the magnitude of the pressure applied is determined according to the electrical signal generated by the positive and negative charges; wherein, although the positive and negative charges are accumulated at two ends of the piezoelectric material layer respectively, the piezoelectric material layer is still an insulator.
However, when the force touch sensor is applied to a flexible display device, because bending will also generate an electrical signal, a misrecognition is liable to occur in pressure sensing when the flexible display device is bent.